Control thermostat for gas heating devices



March 28, 1950 J SHERLOCK 2,502,283 E CONTROL THERMOSTAT FOR GAS HEATING DEVICES Filed Jan. 5, 1946 3 Sheets-Shet l -J. E. SHERLOCK 2,502,283 CONTROL THERMOSTAT FOR GAS HEATING DEVICES Marcus, .1950

Filed Jan. 5, 1946 Y v f s sneets-sne'et'z v Ml/e/rlop ML QW March 28, 1950 J. E. SHERLOCK 2,502,283

' CONTROL mamosTA'r FOR GAS HEATING nsvxcas Filed Jan. 5, 1946 3 Sheets-Sheet 3 Patented Mar. 28, 195i) CONTRGL THERMOSTAT FOR GAS HEATING DEVICES John Edward Sherlock, Sunbury-on-Thames, England, assignor to The'BritishThermostat Company Limited, Sunbury-on-Thames, England, a British company Application January'5, 1946, Serial No. 639,372 In Great Britain October 6', 1944 1. Claim.

This invention relates to control thermostats for use with gas heating devices, and has particular, although not exclusive, reference to heaters of the kind employed in refrigerators, the object of the invention being to provide a combined heater and thermostatic valve for controlling the same, which can be installed in the refrigerator or other apparatus as a complete self-contained unit.

According to the invention a thermostatically controlled gas heating device comprises a casing enclosing a thermally responsive element, a control valve and range adjustment mechanism, the said casing also supporting a gas burner thereby enabling the device as a whole to be mounted as a unit in a refrigerator or other apparatus wherein the temperature of operation is to be controlled.

Reference will now be made to the accompanying drawings which show arrangements according to the invention and in which Fig. 1 is an elevation showing a gas heating device applicable to a refrigerator,

Fig. 2 is another elevation taken at right angles to Fig. 1,

Fig. 3 is a sectional elevation corresponding to Fig. l on an enlargedscale,

Fig. 4 is a sectional elevation corresponding to Fig. 2 on an enlarged scale,

Fig. 5 is a plan of the gas burner shown in Figs. 2 and 4:, and,

Fig. 6 is a detail view of the range cam.

Referring first to Figs. 1 and 2, the improved thermostatically controlled heating device comprises a gas burner I mounted directly on the casing or body 2 of a thermostatic control valve, both burner and casing being supported by a common element which, in the case of a refrigerator, may conveniently be an angle bracket 3 which is constructed to fit on to the boiler tube 4 of a refrigerator in which position it is adapted to be secured by means of clamping screws or similar fixing devices. A nut 5 secures the base portion 6 of the bracket to the lower end of the pipe 1 which supports the burner.

The thermal unit (see Figs. 3 and 4) consists of a bellows chamber 8 secured in the top of the casing 2 and connected by a capillar tube 9 to a coil H] which is adapted to be inserted in a pocket or recess in the evaporator unit of the refrigerator. The expansible bellows II is connected by a valve stem 2 with a valve member l3 controlling the supply of gas from an inlet M to the gas burner l. The working temperature can be adjusted by operation of a control knob l5 mounted at the front of the refrigerator casing and coupled to the thermostat by a long spindle l6. which at its inner end carries a range adjustment cam ll adapted to vary the tension of a range spring l8, one end of which bears upon the movable inner end IQ of the bellows unit and the other end of which bears upon a slide 20 mounted concentrically around the stem l2. The cam ll bears upon a stud 2i carried in the slide 29 whose vertical position inthe casing is thereby adjustable. A second spring 22 is provided to act on the valve head l3 to apply a pre-load to supplement the initial load of the range spring 18.

The profile of the range cam I I isshown in Fig.

. 6.. When. the portion a of the cam is in contact with the stud 2!, a permanently on positionis provided but by rotational adjustment of the cam its surface portion 17 which extends through approximately imparts a gradual increase to the compression of the spring it thereby varying the working temperature. When the portion 0 of the peripher of the cam is in contact with thestud 21., the off position is reached wherein the slide 2!! abuts against the bellows plate It and holds. it stationary thereby keepingthe valve member l3in itsclosed position. A stop 01 is provided to prevent complete rotation of the cam.

The range is initially adjusted by screwing the stem I2 in or out of the bellows plate 19 for which purpose the end of the stem is formed with a slot 23. To provide a by-pass when the valve is seated, the valve member i3 is formed with a central aperture 24 which maintains communication between the inlet chamber 25 and the burner by way of the slot 23 and annular space 26 surrounding the lower end of the valve stem. This by-pass ensures that a small amount of gas will be supplied to the burner i even when the valve member i3 is closed upon its seating, so as to provide a minimum flame to serve as a pilot light. A bafile 28 is fixed in the casing 2 above the valve seating 2? seats to prevent a temporary vacuum occurring in the feed pipe to the gas burner i when the off position is suddenly attained. A slotor aperture formed in the peripheral downwardly extending flange of the baffle member permits gas from the inlet chamber 25 to pass freely towards the burner l. The battle member 28 has a central aperture through which the valve stem I2 is slidable. It is to be understood that part of the chamber within which the slide 20 moves is permanently isolated from the gas feed pipe between the inlet chamber 25 and the burner I, so that a sudden change of pressure in the space above the bafile resulting from a rapid upward move- 3 ment of the slide 20 is not allowed to disturb the flow of gas through the aperture 24 of the Valve member 13, as such a disturbance might result in the pilot flame being extinguished.

The gas burner I employed in the apparatus above described is preferably formed as shown in Figs. 2, 4 and with three jets 29 arranged concentrically around a central axis, to give a more uniform distribution of the flame in the boiler tube than can be obtained with a single jet.

The gas burner comprises a ceramic body 30 generally cylindrical in form and from the upper surface or" which the three equi-spaced jets 29 project. The ceramic body is formed with gas passages 31 which extend throughout its height, one of such passages being arranged ce'ntrally or" each jet 29. The ceramic body 30 is mounted within a metal housing 32 from the base of which depends a portion 33 having a screw-thread 34 to enable it to be mounted in the gas pipe 7 having a standard gas thread. The base of this screw-threaded portion is closed save for a small central aperture 35 for restricting and regulating the gas flow. The component parts of the gas burner are held together by an inwardly directed shoulder 36 on the housing 32 which shoulder engages over a shoulder 3'! formed on the ceramic body.

By raising the jets 29 above the upper surface of the ceramic body, as shown, air is admitted to the spaces between the jets thereby avoiding the production of a smoky flame and obviating the necessity for a central air inlet.

2 The invention possesses the advantage that it can be applied as a unit to existing refrigerators and other apparatus wherein a predetermined temperature is to be maintained and requires no structural alteration as the bracket can be clamped around the particular component which has to be heated.

Having now particularly described and ascertained the nature of my said invention, and in what manner the same is to be performed, I declare that what I claim is:

A thermostatic control for a gas heating device for use in a refrigerator, comprising a casing having a gas inlet and an outlet for supplying gas to a burner, an e'xpansible and contractable thermally responsive element enclosed in the casing, a control valve between the inlet and outlet, an actuating rod between said thermally responsive element and said control valve, a manually operable range setting device, a slide movable by said setting device and adjustable thereby into a position to contract the thermally responsive element and prevent expansion thereof and to seat said control valve, said control valve having a head provided with an aperture for the flow of a small amount of gas to the burner to provide a minimum flame to serve as a pilot light, and means to prevent extinction of said pilot light by creation of a temporary vacuum in said outlet on sudden movement of said slide to contract said thermally responsive element, comprising a bafile mounted in said casing between said control valve and said thermally responsive element and outlet and having an aperture therein communicating with the aperture in said valve head to maintain flow of gas therefrom to the outlet to the burner when said thermally responsive element is suddenly contracted.

JOHN EDWARD SHERLOCK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,570,446 Mombaruzzo Jan. 19, 1926 1,920,458 Bast Aug. 1, 1933 1,961,325 Andersson June 5, 1934 2,040,174 I-Iainsworth May 12, 1936 2,046,643 Mackintosh July 7, 1936 2,093,693 Dillman Sept. 21, 1937 2,123,921 Andersson July 19, 1938 2,140,947 Andersson et al. Dec. 20, 1938 2,151,040 Malone Mar. 21, 1939 FOREIGN PATENTS Number Country Date 503,342 Great Britain Apr. 5, 1939 

